Subtract.
Explanation: There are many ways to solve this problem. Let's see two ways we can solve it. Place Value We can think in terms of hundredths: $\begin{aligned} &\phantom{=}3.49 - 1\\\\ &=3.49 - 1.00\\\\ &=349\text{ hundredths} - 100\text{ hundredths}\\\\ &=249\text{ hundredths}\\\\ &=2.49 \end{aligned}$ Place value table Let's line up the numbers by their decimal places. Ones $.$ Tenths Hundredths ${3}$ $.$ ${4}$ $9$ $1$ $.$ ${0}$ $0$ Now, let's subtract each place value column. Ones $.$ Tenths Hundredths ${3}$ $.$ ${4}$ ${9}$ $-$ $1$ $.$ ${0}$ $0$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $2$ $.$ $4$ $9$ $2.49=3.49 - 1$